AU2022252372A1 - Aqueous chrome-free surface treatment agent, surface treatment metal, and surface treatment method - Google Patents

Abstract

Provided is an aqueous chrome-free surface treatment agent capable of forming a film that can withstand high-strength workability on metal substrates.　The aqueous chrome-free surface treatment agent includes a bifunctional silane compound (A), a monofunctional silane compound (B), and an acetylene glycol-based surfactant (C) It is preferable for the concentration of the bifunctional silane compound (A) to be in the range of 1-100 g/L, the concentration of the monofunctional silane compound (B) to be in the range of 1-100 g/L, and the concentration ratio (A/B) of the bifunctional silane compound (A) to the monofunctional silane compound (B) to be in the range of 0.1-5.

Description

DESCRIPTION

Title of the Invention: AQUEOUS CHROME-FREE SURFACE TREATMENT

AGENT, SURFACE TREATMENT METAL, AND SURFACE TREATMENT METHOD TECHNICAL FIELD

[0001]

The present invention relates to an aqueous chromium-free

surface treatment agent, a surface treated metal, and a

surface treatment method.

BACKGROUND ART

[0002]

Conventionally, as surface treatment agents for imparting

corrosion resistance to metal base materials, chromium-based

metal surface treatment agents such as a chromate treatment

agent and a phosphate chromate treatment agent have been

known, and are also currently widely used. However, recent

trends in environmental regulations may limit the use of

chromium-based metal surface treatment agents in future due to

toxicity, especially carcinogenicity, of chromium.

[0003]

Therefore, various chromium-free metal surface treatment

agents that exhibit corrosion resistance equivalent to that of

chromium-based metal surface treatment agents have been

developed. For example, Patent Document 1 discloses a composition for metal surface treatment, which contains a titanium compound and/or a zirconium compound and a condensation reaction product of aminosilane and polysilyl functional silane.

[0004]

Patent Document 1: Japanese Unexamined Patent Application,

Publication No.2011-068930

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

[0005]

When a film is formed on a metal base material using a

chromium-free metal surface treatment agent, for example, when

the metal base material is used for precoated metal

applications, the film to be formed is required to have

coating adhesion that can withstand high-strength workability

in addition to corrosion resistance. However, it cannot be

said that conventional chromium-free metal surface treatment

agents have sufficient coating adhesion when high-strength

processing is carried out on the metal base material after

surface treatment, and there has been room for improvement.

For example, in the case of a treatment agent including a

silane coupling agent as a main component as described in

Patent Document 1, when the metal base material as an object

to be coated has a smooth surface, a uniform coating cannot be

formed on the metal surface due to occurrence of paint repellency during painting, and the paint adhesion has not been sufficient.

[00061

The present invention has been made in view of the above,

an object of the present invention is to provide an aqueous

chromium-free metal surface treatment agent capable of forming

a film that can withstand high-strength workability on a metal

base material.

Means for Solving the Problems

[0007]

(1) The present invention relates to an aqueous chromium

free surface treatment agent including a bifunctional silane

compound (A), a monofunctional silane compound (B), and an

acetylene glycol-based surfactant (C).

[00081

(2) The aqueous chromium-free surface treatment agent

described in (1), wherein a concentration of the bifunctional

silane compound (A) is in a range of 1 to 100 g/L,

a concentration of the monofunctional silane compound (B) is

in a range of 1 to 100 g/L, and

a concentration ratio (A/B) of the bifunctional silane

compound (A) to the monofunctional silane compound (B) is in a

range of 0.1 to 5.

[00091

(3) The aqueous chromium-free surface treatment agent

described in (1) or (2), wherein a concentration of the acetylene glycol-based surfactant (C) is in a range of 0.05 to

1 g/L.

[0010]

(4) The aqueous chromium-free surface treatment agent

described in any one of (1) to (3), wherein a contact angle on

a mirror-finished aluminum sheet surface is 25 degrees or

less.

[0011]

(5) The aqueous chromium-free surface treatment agent

described in any one of (1) to (4), further including water

dispersible metal oxide particles (D), wherein an average

particle diameter of the water-dispersible metal oxide

particles (D) is 150 nm or less, and a concentration of the

water-dispersible metal oxide particles (D) is in a range of 1

to 20 g/L.

[0012]

(6) The aqueous chromium-free surface treatment agent

described in any one of (1) to (5), further including a

polyurethane resin (E) that is at least any one of a water

dispersible polyurethane resin and a water-soluble

polyurethane resin, and a concentration of the polyurethane

resin (E) is in a range of 1 to 20 g/L.

[0013]

(7) The aqueous chromium-free surface treatment agent

described in any one of (1) to (6), further including a block

isocyanate resin (F), and the concentration of the block isocyanate resin (F) is in the range of 1 to 20 g/L.

[0014]

(8) The aqueous chromium-free surface treatment agent

described in any one of (1) to (7), in which pH of the aqueous

chromium-free surface treatment agent is in a range of 5 to 7.

[0015]

A surface treated metal including a surface on which a

surface treatment film is formed with an aqueous chromium-free

surface treatment agent according to any one of (1) to (8).

[0016]

(10) A surface treatment method including a surface

treatment film formation step including treating a surface of

an object to be coated with an aqueous chromium-free surface

treatment agent according to any one of the above (1) to (8).

Effects of the Invention

[0017]

The present invention can provide an aqueous chromium-free

metal surface treatment agent capable of forming a film that

can withstand high-strength workability on a metal base

material.

PREFERRED MODE FOR CARRYING OUT THE INVENTION

[0018]

Hereinafter, an aqueous chromium-free surface treatment

agent, a surface treated metal, and a surface treatment method

in accordance with embodiments of the present invention will be described. The present invention is not limited to the embodiments described below.

[0019]

<Aqueous chromium-free surface treatment agent>

An aqueous chromium-free surface treatment agent of this

embodiment includes a bifunctional silane compound (A), a

monofunctional silane compound (B), and an acetylene glycol

based surfactant (C). Furthermore, it is preferable that the

aqueous chromium-free surface treatment agent further includes

at least any one of a water-dispersible metal oxide particles

(D), a polyurethane resin (E), and a block isocyanate resin

(F).

[0020]

(Bifunctional silane compound (A))

A bifunctional silane compound (A) is a compound including

two silanol groups or silyl groups capable of forming a

silanol group by hydrolysis in a molecule. Examples of the

bifunctional silane compound (A) include a compound

represented by the following formula (I).

[0021]

[Chem. 1]

(Xi)a-a-(R')a(R 2 )bSi-Y-Si(RW)(R 4)(X 2 )3-0d '41 (I)

[0022]

In the above formula (1), R1, R 2 , R 3 , and R 4 each independently represent a hydrogen atom, or a monovalent organic group having 1 to 30 carbon atoms. Examples of the monovalent organic group include hydrocarbon groups such as an alkyl group, an alkenyl group, a cycloalkyl group, and an aryl group; hydrocarbon groups having functional groups such as a hydroxyl group, an epoxy group, and an amino group. As the monovalent organic group, an alkyl group having 1 to 4 carbon atoms such as a methyl group or an ethyl group is preferable.

[0023]

In the above formula (I), Y represents a divalent organic

group or amine. Examples of the divalent organic group include

an alkylene group, an alkyleneoxy group, an alkylenethio

group, or groups including the above divalent organic group as

a partial structure. As the divalent organic group, an

alkylene group is preferable. The number of carbon atoms in

the divalent organic group is preferably 2 to 30, and more

preferably 2 to 12.

[0024]

In the above formula (I), X1 and X 2 each independently

represent a hydrolyzable group. Examples of the hydrolyzable

groups include a hydroxyl group and an alkoxy group having 1

to 4 carbon atoms. X1 and X 2 are preferably a hydroxyl group.

When X1 and X 2 are an alkoxy group, the alkoxy group is

preferably a methoxy group or an ethoxy group.

[0025]

In the above formula (1), a and b each independently represent an integer of 0 to 2, and 0 a+b 2 is satisfied.

Furthermore, c and d each independently represent an integer

of 0 to 2, and 0 c+d 2 is satisfied. Both a+b and c+d are

preferably 0 or 1.

[0026]

Specific examples of the bifunctional silane compound (A)

represented by the formula (I) include

bis(trimethoxysilyl)methane, 1,2-bis(trimethoxysilyl)ethane,

1,2-bis(triethoxysilyl)ethane, 1,6-bis(trimethoxysilyl)hexane,

1,6-bis(triethoxysilyl)hexane, 1,8-bis(trimethoxysilyl)octane,

1,8-bis(triethoxysilyl)octane, 1,9-bis(trimethoxysilyl)nonane,

1,9-bis(triethoxysilyl)nonane, bis(trimethoxysilyl)amine,

bis(triethoxysilyl)amine, bis(trimethoxysilylmethyl)amine,

bis(triethoxysilylmethyl)amine,

bis(trimethoxysilylpropyl)amine,

bis(triethoxysilylpropyl)amine, and the like. Among these,

1,2-bis(triethoxysilyl)ethane is preferable from the viewpoint

of safety in handling and corrosion resistance and adhesion of

the obtained film.

[0027]

The bifunctional silane compound (A) may be used alone or

in combination of two or more types thereof. Also, the

bifunctional silane compound (A) may be partially hydrolyzed

or may be condensed by hydrolysis.

[0028]

It is preferable that the concentration of the bifunctional silane compound (A) in the aqueous chromium-free metal surface treatment agent is in the range of 1 to 100 g/L.

[0029]

(Monofunctional silane compound (B))

The monofunctional silane compound (B) is a compound

having one silanol group or a silyl group capable of forming a

silanol group by hydrolysis in one molecule. Examples of the

monofunctional silane compound (B) include amino group

containing silanes such as 3-aminopropyltriethoxysilane, 3

aminopropyltrimethoxysilane, N-2-(aminoethyl)-3

aminopropyltrimethoxysilane, N-2-(Aminoethyl)-3

aminopropylmethyldimethoxysilane, 3

aminopropylmethyldimethoxysilane, 3

aminopropylmethyldiethoxysilane, N-phenyl-3

aminopropyltrimethoxysilane, N-phenyl-3

aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl

butylidene)propylamine, and N-phenyl-3

aminopropyltrimethoxysilane; epoxy group-containing silanes

such as 3-glycidoxypropyltrimethoxy silane, 3

glycidoxypropyltriethoxysilane, 3

glycidoxypropylmethyldimethoxysilane, 3

glycidoxypropylmethyldiethoxysilane, 2-(3,4

epoxycyclohexyl)ethyltrimethoxysilane; monosilanol compounds

such as trimethylsilanol and triethylsilanol;

monochlorosilanes such as trimethylchlorosilane and

triethylchlorosilane; monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane; and monoacyloxysilanes such as trimethylacetoxysilane. Among these, amino group-containing silanes are preferable, and 3 aminopropyltriethoxysilane is more preferable.

[00301

The monofunctional silane compound (B) may be used alone

or in combination of two or more types thereof. Also, the

monofunctional silane compound (B) may be partially hydrolyzed

or may be condensed by hydrolysis.

[0031]

It is preferable that the concentration of the

monofunctional silane compound (B) in the aqueous chromium

free metal surface treatment agent is in the range of 1 to 100

g/L.

[0032]

The concentration ratio (A/B) of the bifunctional silane

compound (A) to the monofunctional silane compound (B) is

preferably in the range of 0.1 to 5, and more preferably in

the range of 0.25 to 2.5. When the concentration ratio (A/B)

is more than 5, the number of hydrogen bonds at the interface

between the film and the coating film is reduced, resulting in

a reduction in strength and a reduction in adhesion to the

coating film. When the concentration ratio (A/B) is less than

0.1, the hydrophilicity of the film becomes high, which makes

it easier for moisture to permeate, and the corrosion

resistance and coating adhesion after coating are lowered.

[0033]

(Acetylene glycol-based surfactant (C))

An acetylene glycol-based surfactant (C) is a nonionic

surfactant having an acetylene group. When the acetylene

glycol-based surfactant (C) is contained in the aqueous

chromium-free metal surface treatment agent together with the

bifunctional silane compound (A) and the monofunctional silane

compound (B), the wettability of the aqueous chromium-free

metal surface treatment agent with respect to the metal base

material that is an object to be coated can be improved. For

example, the contact angle with respect to the metal base

material can be adjusted to 25 degrees or less. Thus, a

uniform coating film can be formed on the metal base material.

Examples of the acetylene glycol-based surfactant (C) include

compounds represented by the following formula (II).

[0034]

[Chem. 2]

R's R6 I I H..1C,.- C - C C - C - CH. -(I I | 0-R7 0-R8

[0035]

In the above formula (II), R 5 and R 6 each independently represent a hydrogen atom or a methyl group. In the above formula (II), R7 and R8 each independently represent a hydrogen atom or an alkylene group. Examples of the alkylene group include an ethylene group and a propylene group. In other words, the acetylene glycol-based surfactant (C) may be an alkylene oxide addition type or an alkylene oxide non-addition type.

[00361

In the above formula (II), n and m each independently

represent an integer of 1 to 10.

[0037]

As the acetylene glycol-based surfactant (C) represented

by the formula (II), commercially available products can be

used. Examples of commercially available products include

Surfynol (Surfinol 104, Surfynol 465, and the like)

manufactured by Nissin Chemical Industry Co., Ltd., and

Olphine series manufactured by Air Products. The acetylene

glycol-based surfactant (C) may be used alone or in

combination of two or more types thereof.

[00381

The concentration of the acetylene glycol-based surfactant

(C) in the aqueous chromium-free metal surface treatment agent

is preferably in the range of 0.05 to 1 g/L, and more

preferably in the range of 0.1 to 0.5 g/L.

[00391

(Water-dispersible metal oxide particles (D))

The water-dispersible metal oxide particles (D) are metal

oxide particles having water-dispersible property, such as Zr

oxide, Ti oxide, Si oxide, Al oxide, Ce oxide, Nb oxide, Nd

oxide, Sn oxide, Nd oxide, and La oxide. Containing of the

water-dispersible metal oxide particles (D) in the aqueous

chromium-free metal surface treatment agent can suppress the

brittle collapse of the film formed and further improve the

coating adhesion that can withstand high-strength processing.

The water-dispersible metal oxide particles (D) are preferably

Zr oxide. The water-dispersible metal oxide particles (D) may

be used alone or in combination of two or more thereof.

[0040]

The concentration of the water-dispersible metal oxide

particles (D) in the aqueous chromium-free metal surface

treatment agent is preferably in the range of 1 to 20 g/L, and

more preferably in the range of 2 to 15 g/L.

[0041]

The average particle diameter (the median diameter D50

measured by a dynamic light scattering method) of the water

dispersible metal oxide particles (D) is preferably 150 nm or

less, and more preferably 10 nm to 120 nm.

[0042]

(Polyurethane resin (E))

The polyurethane resin (E) is at least any one of a water

dispersible polyurethane resin and a water-soluble

polyurethane resin. In other words, the polyurethane resin (E) has either water solubility or water dispersibility.

Containing of the polyurethane resin (E) in the aqueous

chromium-free metal surface treatment agent can suppress the

brittle collapse of the film formed and further improve the

coating adhesion that can withstand high-strength processing.

The polyurethane resin (E) is not particularly limited, and

can be obtained, for example, by polymerizing a polyol

compound and a polyisocyanate compound by a conventionally

known method. The polyurethane resin (E) may be used alone or

in combination of two or more types thereof.

[0043]

The polyol compound is not particularly limited, and

conventionally known synthetic raw materials can be used.

Examples thereof include polyester polyols, polyesteramide

polyols, polyether polyols, polythioether polyols,

polycarbonate polyols, polyacetal polyols, polyolefin polyols,

polysiloxane polyols, and the like.

[0044]

The polyisocyanate compound is not particularly limited,

and conventionally known synthetic raw materials can be used.

Examples thereof include aliphatic isocyanate, alicyclic

diisocyanate, aromatic diisocyanate, aromatic-aliphatic

diisocyanate, and the like.

[0045]

The concentration of the polyurethane resin (E) in the

aqueous chromium-free metal surface treatment agent is preferably in the range of 1 to 20 g/L, more preferably in the range of 5 to 15 g/L in terms of resin solid content.

[0046]

(Block isocyanate resin (F))

A block isocyanate resin (F) is a water-soluble resin that

reacts with the polyurethane resin (E) to form a crosslinked

structure. The block isocyanate resin (F) is a polycondensate

of compounds (monomers) having at least one block isocyanate

group in a molecule blocked with blocking agents such as

phenolic, alcoholic, oxime, active methylene, acid amide,

carbamate, and sulfite blocking agents.

[0047]

A block isocyanate resin (F) is obtained by adding a

blocking agent to a compound having at least one isocyanate

group in one molecule. Examples of the compounds having at

least one isocyanate group in one molecule include aliphatic

diisocyanates such as hexamethylene diisocyanate (including

trimer), tetramethylene diisocyanate and trimethyl

hexamethylene diisocyanate, alicyclic polyisocyanates such as

isophorone diisocyanate, and 4,4'-methylenebis(cyclohexyl

isocyanate), and aromatic diisocyanates such as 4,4'

diphenylmethane diisocyanate, tolylene diisocyanate, and

xylylene diisocyanate. The block isocyanate resin (F) may be

used alone or in combination of two or more types thereof.

[0048]

The concentration of the block isocyanate resin (F) in the aqueous chromium-free metal surface treatment agent is preferably in the range of 1 to 20 g/L, and more preferably 5 to 15 g/L in terms of resin solid content.

[0049]

(Other compounds)

The aqueous chromium-free metal surface treatment agent in

accordance with this embodiment may further contain components

other than the components described above. Examples of other

components include cross-linking agents other than those

mentioned above that promote curing of the resin, surface

conditioning agents used for leveling, defoaming agents used

for suppressing foam, and the like.

[0050]

(pH of aqueous chromium-free metal surface treatment agent)

The aqueous chromium-free metal surface treatment agent in

accordance with this embodiment preferably has a pH in the

range of 5 to 7. When the pH of the aqueous chromium-free

metal surface treatment agent is 7 or less, the storage

stability is further improved.

[0051]

(Contact angle of aqueous chromium-free metal surface

treatment agent)

The aqueous chromium-free metal surface treatment agent in

accordance with this embodiment has a contact angle of 25

degrees or less on a mirror-finished aluminum sheet surface.

Therefore, a film having good wettability with respect to a metal base material as an object to be coated and being uniform can be formed. Accordingly, as a result, the coating adhesion can be improved. The mirror-finished aluminum sheet, which is polished by buffing with an ultrafine abrasive until the surface roughness Rz of the aluminum sheet reaches 0.05 to

0.2 pm, and the surface is washed with a degreasing agent (for

example, Surf Cleaner 155 manufactured by Nippon Paint Surf

Chemicals Co., Ltd.) and water, can be used. As the contact

angle, a value of a static contact angle measured using a

contact angle meter (for example, DSA20E manufactured by

KRUSS) in a thermostatic chamber in which the temperature is

set at 20 0 C.

[0052]

<Surface treatment method>

A surface treatment method in accordance with this

embodiment includes a surface treatment film formation step

including treating a metal base material as an object to be

coated with the aqueous chromium-free metal surface treatment

agent in accordance with this embodiment so as to form a

surface treated film. The surface treatment film formation

step includes applying an aqueous chromium-free metal surface

treatment agent to, for example, a surface of the metal base

material as an object to be coated, and drying the metal base

material to which aqueous chromium-free metal surface

treatment agent has been applied so as to form a film.

[0053]

(Applying)

In the applying, the method for applying the aqueous

chromium-free metal surface treatment agent to the metal base

material is not particularly limited, and examples thereof

include roll coater coating, brush coating, roller coating,

bar coater coating, flow coating, and the like.

[0054]

(Drying)

A drying method in the drying is not particularly limited,

and a known method can be used. A drying temperature in the

drying is preferably, for example, 60 to 900C in the peak

metal temperature, which is the temperature reached by the

surface of the metal base material.

[0055]

The applying and the drying may be carried out

simultaneously. For example, an aqueous chromium-free metal

surface treatment agent is applied to the preheated metal base

material and dried using residual heat.

[0056]

A film amount of the aqueous chromium-free metal surface

treatment agent in the surface treatment film formation step

is, after drying, preferably in the range of 0.1 to 500 mg/m 2 ,

and more preferably in the range of 1 to 250 mg/m2 .

[0057]

The surface treatment method in accordance with this

embodiment may further apply primer coating or top coating to the metal base material on which a film is formed by the surface treatment film formation step.

[00581

<Surface treated metal>

The surface treated metal in accordance with this

embodiment is formed by forming a surface treatment film on

the surface of the metal base material as an object to be

coated with the aqueous chromium-free surface treatment agent

in accordance with the embodiment mentioned above. The metal

base material is not particularly limited, and examples

thereof include an aluminum sheet, a stainless steel sheet, or

a zinc-based plated steel sheet such as a galvanized steel

sheet, a zinc alloy plated steel sheet, and a hot-dip

galvanized steel sheet. Furthermore, the metal base material

may be a base material to which the surface treatment film has

been formed and then subjected to laminate processing by

laminate film.

[00591

Examples of the aluminum sheet include 3000 series

aluminum alloy, 4000 series aluminum alloy, 5000 series

aluminum alloy, 6000 series aluminum alloy, and aluminum

plated steel sheets by aluminum-based electroplating, hot

dipping, or vapor deposition plating.

[00601

Examples of the stainless steel sheets include SUS 300

stainless steel and SUS 400 stainless steel.

[00611

Examples of the zinc-based plated steel sheet include zinc

or zinc-based alloy plated steel sheets by zinc-based

electroplating, hot dipping, or vapor deposition plating, such

as zinc plated steel sheet, zinc-nickel plated steel sheet,

zinc-iron plated steel sheet, zinc-chromium plated steel

sheet, zinc-aluminum alloy plated steel sheet such as zinc-55

wt.% aluminum alloy plated steel sheet, zinc-titanium plated

steel sheet, zinc-magnesium plated steel sheet, and zinc

manganese plated steel sheet.

[0062]

As the laminate film, for example, a resin film is used.

Examples of the resin film include thermoplastic resins such

as polyethylene terephthalate (PET), polyethylene naphthalate

(PEN), polypropylene (PP), polycarbonate (PC), triacetyl

cellulose (TAC), polyvinyl chloride (PVC), polyester,

polyolefin, polyphenylene sulfide (PPS) and acrylic. The

lamination processing method for laminating the laminate film

is not particularly limited, and examples thereof include a

dry lamination method and an extrusion lamination method.

EXAMPLES

[00631

The present invention will be described in more detail

below based on Examples, but the present invention is not

limited by these Examples.

[0064]

<Preparation of aqueous chromium-free surface treatment agent>

[Example 1]

An aqueous chromium-free surface treatment agent of

Example 1 was obtained by mixing and stirring components (A),

(B), and (C) in ion-exchanged water to obtain concentrations

listed in Table 1. As the bifunctional silane (A), previously

hydrolyzed 1,2-bistriethoxysilylethane ("KBE-3026"

manufactured by Shin-Etsu Chemical Co., Ltd.) was used. As the

monofunctional silane (B), 3-aminopropylethoxysilane ("KBE

903" manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

As the active agent (C), Surfynol 104 (acetylene glycol-based

surfactant, ethylene oxide addition type) manufactured by Air

Products was used.

[0065]

[Examples 2 to 21, Comparative Examples 1 to 5]

In Example 19, pre-hydrolyzed bis(triethoxysilyl)amine

(Dynasylan 1124 manufactured by EVONIC) was used as the

bifunctional silane (A) component. In Example 20, 3

glycidoxytriethoxysilane (KBE-403 manufactured by Shin-Etsu

Chemical Co., Ltd.) was used as the monofunctional silane (B).

In Example 21, Surfynol 465 (acetylene glycol-based

surfactant, non-ethylene oxide addition type) manufactured by

Air Products was used as the active agent (C). In Comparative

Example 4, Newcol 1000 (alkyl ether-based surfactant)

manufactured by Nippon Nyukazai Co., Ltd. was used as the active agent (C). In Comparative Example 5, a hexavalent chromium-containing treatment agent (Surfcoat NRC300 manufactured by Nippon Paint Surf Chemicals Co., Ltd.) was used in place of the aqueous chromium-free surface treatment agent. Procedures were the same as in Example 1 except for the above.

[00661

<Production of test sheet>

Using the surface treatment agents of Examples 1 to 21 and

Comparative Examples 1 to 5, 3000 series and 5000 series

aluminum sheets (manufactured by Nippon Test Panel Co., Ltd.,

sheet thickness: 0.35 mm) as metal base materials shown in

Table 1 were subjected to surface treatment, respectively. The

surface treatment was carried out according to the following

procedures. The aluminum sheet was degreased by spraying Surf

Cleaner 155 (manufactured by Nippon Paint Surf Chemicals Co.,

Ltd.) as an alkaline degreasing agent at 60°C for 10 seconds,

spray-washed with water, and dried, and then a surface

treatment agent was applied to the aluminum sheet using a bar

coater #3, followed by drying at a PMT (peak metal

temperature) of 80 0 C. In Comparative Example 5, after

degreasing, washing with water, and drying, the applying was

carried out using a bar coater so that an adhering amount of

chromium was 30 mg/m 2, followed by drying at a PMT of 60 0 C. To

the aluminum sheet surface-treated by the above method, a

thermosetting acrylic clear paint (Super Rack D1F R-37 Gold matte (modified) AP, manufactured by Nippon Paint Industrial

Coatings Co., Ltd.) was applied so that a dry film thickness

became 5 pm, then baked and dried at a PMT of 2500C for 50

seconds to obtain test sheets of Examples 1 to 21 and

Comparative Examples 1 to 5.

[0067]

<Evaluation>

[Bending primary adhesion]

In an environment of 20°C, the test sheet was bent 1800

without a spacer (OTT), or bent 1800 with two 0.35 mm aluminum

sheets as a spacer sandwiched therebetween (2TT). The bent

portion was subjected to a tape peeling three times, and the

degree of peeling was observed using a magnifying glass having

an enlargement factor of 20 times and evaluated according to

the following criteria. The results are shown in Table 1 with

4 or more regarded as acceptable.

: No peeling was observed, 4.5: 1 to 10% peeling, 4: 11 to

% peeling, 3.5: 21 to 30% peeling, 3: 31 to 40% peeling,

2.5: 41 to 50% peeling, 2: 51 to 60% peeling, 1.5: 61 to 70%

peeling, 1: 71 to 80% peeling, 0.5: 81 to 90% peeling, 0: 91

to 100% peeling

[0068]

[Bending secondary adhesion]

The test sheet was immersed in boiling water for 2 hours,

allowed to stand in a room for 24 hours, and was evaluated

according to the same criteria under the same conditions as

OTT and 2TT as in the primary bending adhesion. The results

are shown in Table 1 with 3.5 or more regarded as acceptable.

[00691

[Filiform corrosion length]

A test sheet in which a cross-cut had been made was placed

in a 2-L beaker containing 50 mL of concentrated hydrochloric

acid, exposed to hydrochloric acid vapor for 10 minutes, and

placed in a constant temperature and humidity cell at 400C and

RT 82%. The filiform corrosion from the cut part after 250

hours was measured in the length of and the number of chips

(number of filiform corrosion), and the total length of

filiform corrosion was calculated. The length of 2 mm or less

was regarded as acceptable. The results are shown in Table 1.

[0070]

[SST (Salt spray test)]

A test sheet in which a cross-cut had been made was placed

in a salt spray corrosion tester specified in JIS Z2317 for

1000 hours, and the average width of corrosion blistering from

the cut part on one side and the average width of corrosion

blistering from the end surfaces (upper and lower flashes)

were measured. Less than 1 mm was regarded as acceptable. The

results are shown in Table 1.

[0071]

[CCT (Composite cycle corrosion Test)]

A test sheet in which a cross-cut had been made was placed

in a combined cycle corrosion tester specified in JIS K5621 for 1000 hours, and the average width of corrosion blistering from the cut part on one side and the average width of corrosion blistering from the end surfaces (upper and lower flashes) were measured. Less than 1 mm was regarded as acceptable. The results are shown in Table 1.

[0072]

[Contact angle measurement]

The surface treatment agents of Examples 1 to 21 and

Comparative Examples 1 to 4 were set in an automatic contact

angle meter (DSA20E manufactured by KRUSS), and the static

contact angles with the treatment agents dropped on the

aluminum sheet were respectively measured in a constant

temperature room of 20°C. The aluminum sheet, which had been

polished by buffing using an ultrafine abrasive polisher until

the surface roughness Rz of the aluminum sheet had become 0.05

to 0.2 pm, and the surface had been degreased with a

degreasing agent (Surf Cleaner 155 manufactured by Nippon

Paint Surf Chemicals Co., Ltd.) at 60°C for 30 seconds and

then washed with water, was used. The contact angle of 25

degrees or less was regarded as acceptable, and the results

are shown in Table 1.

[0073]

[Table 1]

U a) m-nCD omN- DCD oTNCmm- m 'T'TU'T r' -Jm aa r- Jo 'J ( o O m y a N -

' o 0 eo

Q)E 00 0U 0 0 C_ _ _ _

E o E E

LCU:00 CDCDC C 0 D CDC C D OCDC 00 t

a

oE q003 0000 0 0 0 OOLN _ 0 m C00 ODOD000 N L N

E E -o o CDm ooo0 o'oToo C Nm

> t e e

E o

enE o n nnwo mmm mm amm n n

E 0 cD m m D.D CD NN N

e ca

0 0 0En

En C) M

0e E

co~~ ~Qn Un) L n nn inn Ln Lnn Ln U)U )U T' ' TmU U TN n 66 6 dd dd a daa666 '

E - - - - - - - - - - - - - - - )

a c) o o) Un U)Ln m m mo o mn m no U) Un U) Un Un Un , ) n n n 0) a) a ° E

To0 0 o

E c 0 Qa) c .- o N (N N(No

0iwx iwx r- E 0 0

Q c I 'T m CD O N 'T r CD O miw Nex T 0m m m U)

[0074]

[Examples 22 to 38, Comparative Examples 6 to 9]

Metal oxide particles (D) of the types and amounts shown

in Table 2 were further added. In Comparative Example 9, a

hexavalent chromium-containing treatment agent (Surfcoat

NRC300 manufactured by Nippon Paint Surf Chemicals Co., Ltd.)

was used in place of the aqueous chromium-free surface

treatment agent. A surface treatment agent was prepared in the

same manner as in Example 1 except for the above. The average

particle diameters (D50) of the metal oxide particles (D)

shown in Table 2 are as shown below. ZrO2: 80 nm, TiO 2 : 10 nm,

SiO 2 : 9 nm, CeO2: 15 nm, Nb 2 05 : 4 nm, SnO2: 2 nm, A1 2 0 3 : 50 nm

[0075]

<Production of test sheet>

Surface treatment was carried out in the same manner as in

Example 1 and Comparative Example 5 except that a zinc-55 wt.%

aluminum alloy plated steel sheet (GL) (manufactured by Nippon

Test Panel Co., Ltd., sheet thickness 0.35 mm) as the metal

base material was subjected to surface treatment. Epoxy

polyester primer paint (NSC5610NC PRIMER manufactured by

Nippon Paint Industrial Coatings Co., Ltd.) was applied to the

GL steel sheet surface-treated by the above method using a bar

coater so that the dry film thickness was 5 pm, and then baked

and dried at a PMT of 215°C, then, a polyester top coat (S/C

490HQ 1C4661 manufactured by Nippon Paint Industrial Coatings

Co., Ltd.) was applied using a bar coater so that the dry film thickness was 15 pm, and baked and dried at a PMT of 2300C to obtain test sheets of Examples 22 to 38 and Comparative

Examples 6 to 9.

[0076]

<Evaluation>

[Bending primary adhesion and bending secondary adhesion]

Tests were carried out in the same manner as in Examples 1

to 21 and Comparative Examples 1 to 5, and evaluated according

to the following criteria. The results are shown in Table 2

with 4 or more regarded as acceptable.

: No cracks, 4: Cracks occur on the entire processed part, 3:

A peeling area is less than 20% of the processed part, 2: A

peeling area is 20% or more and less than 80% of the processed

part, 1: A peeling area is 80% of the processed part.

[0077]

[SST (salt spray test), CCT (combined cycle corrosion test)]

Tests were carried out in the same manner as in Examples 1

to 21 and Comparative Examples 1 to 5, and evaluation was

carried out. For SST, corrosion resistance of the processed

part was further evaluated. The corrosion resistance of the

processed part was evaluated by visually observing the white

rust area rate (%) on the coated surface after the SST test

(2TT) according to the following criteria.

: No rust, 4.5: 0 to 10%, 4: 11 to 20%, 3.5: 21 to 30%, 3: 31

to 40%, 2.5: 41 to 50%, 2: 51 to 60%, 1.5: 61 to 70%, 1: 71 to

%, 0.5: 81 to 90%, 0: 91 to 100%

[0078]

The acceptance criteria for the SST and CCT tests shown in

Table 2 are as follows. SST (corrosion resistance of processed

part): 4 or more, SST (cut part): 1 or less, SST (top and

bottom of end surface): 7 or less, CCT (cut part): 0.7 or

less, CCT (top and bottom of end surface): 3 or less

[0079]

[Table 2] aE _0 .9 U- C O in aO-' Cm i O C C-' l r-.. r-.. r r'j O

E

Co 00 Ctt IN CH IN IN IN IN I N N ICN f f CD L - - - - - - - 1 1 1 1

, CD L

b eNe e N e Ne eNe n N u fu

Q)E c~ Z U ) 0. -1 -1 C r-. C -i eN " -i eN . N i L6 LrL .6o6r- o ,i

. LU 0 m m'r r N NrNr N m r N NrNr

c o-. CU C C k

C> t

U) U) ()

0 u w mo ru - 2 t ~Lf Lfl Ll Lfl Lfl Lfl Lfl U --'G,u- 0- I e 0 'M 0

H- n in in4 0) il c - n in in in in in in in in in in in in in e c 1F, ru 0 2 U.) e

ui _0 H-n in in in in in in in 4 n Q) ru H n in in . n in in in in . n eN U') C0 .13 .13 .13 .13 .1: .3 13 1:

L - n in in in in in in in in in in in in in in in in m , eN 4eN n

H-4

ru H n in in in in in in in in in in in in in in in in m ,N IN in

0) ru

- - -0.) 0m 0) 0.) 0n . N 0 ~C) in 0) m 0) 0) 0) -t-- oio lo lo 1o n .- n- m INn

-. 0 v- 0 2( 2(

E 0)- u - - - - - - - - - - Liu

ru 00a 1- ~n CD in fin t. 00 C=> Cn C0i 4 t.0 C= C= C

,AE 0)0

) u~ 0 00

o Q) 0

0 0 U'I- Zn t , mmr4 mz nt , 0 m m -m-- t---,0) adux olwx @Al-jdo

[0080]

[Examples 39 to 56, Comparative Examples 10 to 13]

The surface treatment agents were prepared and test sheets

were prepared in the same manner as in Examples 22 to 38 and

Comparative Examples 6 to 9 except that metal oxide particles

(D), polyurethane resin (E) (Superflex 650 manufactured by DKS

Co., Ltd.), and block isocyanate resin (F) (Aqua B1220

manufactured by Lanxess Solutions Japan) of types and amounts

shown in Table 3 were further added.

[0081]

[Table 3] r4 w E)~

0 L iC ir C C C C C C 1. 10 . ~LA LALMA%. AM M M 1.0 1. 1.0 M M M ItN mALA

4w 4J LL -u rn Un L C C 0 m o u~ 0

c 0 4-) 7

4-)

cn -. -, I 4-J u 2 2 929NN 0 ONNNNNNN L----LLLL NNNH-N (-WWLZn 2 NNNNNNNNE4

u( E

0 0 L

u 4C) m m It It II. t 10 . . ............ (

<0 0 0

o (a 0 0)N0 D ) 0 0 C: 0

___ _ _ _ _ _ __ _ _ _ _ _ _ __ _ _ _ _ _ _ _ __ _ _ _ __<__ _~ iJd O

[0082]

<Evaluation>

Evaluation was carried out under the same conditions as in

Examples 22 to 38 and Comparative Examples 6 to 9 except that

the SST test and CCT test conditions were changed from 1000 hr

to 1500 hr. The results are shown in Table 4. The acceptance

criteria for the SST and CCT tests shown in Table 4 are as

follows. SST (corrosion resistance of processed part): 3.5 or

more, SST (cut part): 1.5 or less, SST (top and bottom of end

surface): 6.1 or less, CCT (cut part): 0.7 or less, CCT (top

and bottom of end surface): 3.5 or less

[00831

[Table 4]

) E oU'P .- in. .- Nr nJ -in.J I- .- r Nr r eN (N e'iee mm -;

-CC1- o E0 a0 N. M' N Itt oa rn- .t- njnj-- Not U o LU

U U r .)

U ca r oE _0 U 0 50 5 -0 a3) E .0 Na M M N t LO M c E- E.----LU--------------------- ItI t I t I t I t t L D % O U

rLOl aExoamle 57 t o o to Eoxample 1o to 17] > D L) U)

- 2

UO tnLO LOLOLOLOLO LOl LOl LO LOl LOl LOl LOl LflLfl N

HoU_0L LOL a)t cn Hu O 2 LOLOfLOlLflLflLOl LO LLOLf fLOlf LO. N -I -I tq ai Ea e

u-c HO LO L LOlLOfLO r r r Lf Lfl Lfl L MNfl Lfl

C) L

0- ru H O LOLOLOLO fLOlLO LOl LOl LO LOl LOl LOl LO LO LOt t flN N LOl 0 Surface treatmentarr rrern mtesme mane

ru

2Idwex] 2Idwex] 2A!WJedwoj

[Examples 57 to 74, Comparative Examples 14 to 17]

Surface treatment agents were prepared in the same manner

as in Examples 22 to 33 and Comparative Examples 6 to 9 except that metal oxide particles (D), polyurethane resin (E), and block isocyanate resin (F) of the types and amounts shown in

Table 5 were further added, and in Example 65, A1203 as metal

oxide particles (D) having an average particle diameter (D50)

of 100 nm were used. The test sheet was prepared by the same

procedures as in Examples 22 to 38 and Comparative Examples 6

to 9 except that a hot-dip galvanized steel sheet (GI)

(manufactured by Nippon Test Panel Co., Ltd., sheet thickness

0.35 mm) was used as the metal base material and immersed in a

nickel sulfate-based surface conditioner (NP conditioner 700,

pH 3.0, 600C) for 5 seconds after spray washing.

[00851

[Table 5]

E 000 C Mn 10 1 n 00 0 O 0 m0 N00000

o L U :( nJ C L : )0 : )U ) U

w 1 - - -m c m L)L) c c C UJ

5L

2-w

(Jj -- j - j - j j- j - j - - -- 4

>-0 J70 2 4- rM M m n N N N N N-)

a) r OLtL) O u N ro~~On O~. ~0~~ w w-N 00000

UU < N N N

O E U

2 < 0 EU

[00 ] <Evluaion

[Stability]

The liquid stability of the surface treatment liquid after

being left still for 3 months in an incubator at 400C after

preparation was visually evaluated according to the following

criteria.

1: No problem, 2: Somewhat cloudy

[0087]

Evaluation was carried out under the same conditions as in

Examples 22 to 38 and Comparative Examples 6 to 9 except for

the above. The results are shown in Table 6. Note here that

the acceptance criteria for the SST and CCT tests shown in

Table 6 are as follows. SST (corrosion resistance of processed

part): 3.5 or more, SST (cut part): 6.0 or less, SST (top and

bottom of end surface): 6.1 or less, CCT (cut part): 0.7 or

less, CCT (top and bottom of end surface): 3.5 or less

[0088]

[Table 6]

E

E 01 rjr N N N N NN N N NN N M M M N 1- 1

E L. UU o u

EE o u 0U I' 'OO N N r~ r~ M q N N kD0lMfM M m MN M ;.

U wE -o t

U) U C __ 4_ _

o- ui6~ ~ N N N N N N N r r m 0 uU U

0~ 0

mo 00

> Mn

ald 0X 0

[0089]

Cpra _E

The 4s rac reaitmenq t t tM agnt were preare and tes) t sheets*I

0 39

werprpae n the sam manra n Exmpe 22t 3 n Copaatv Exmls6t0 in the same mniner werepreare xetthtea as inExamles xd 22 to atce 38 nd

(D), polyurethane resin (E), and block isocyanate resin (F) of

the types and amounts shown in Table 7 were further added, and

in Example 83, A1203 as metal oxide particles (D) having an

average particle diameter (D50) of 140 nm was used, and the

metal base material was a stainless steel sheet (in Table 7,

304 indicates SUS304, and 430 indicates SUS430) (manufactured

by Nippon Test Panel Co., sheet thickness 0.35 mm).

[00901

[Table 7] ra L U : MMm ') mo WQU ooo0e0ooo nenenenen ooo 000

Wrn

_~rnLU n

0) (10 2 n w

wJ - j - j - j _ -J

_n u N N

U N N NN NN

N N U U <I

E

07 co

<I~ux .2d 0x 4-j 0) - Ln L An 2Jirdi OJ U :Z0091]. . . . T m T NT m L c<Evaluation> rm 0

Evaluation was carried out in the same manner as in

Examples 57 to 74 and Comparative Examples 14 to 17 except

that the SST and CCT were set to 1500 hours. The results are

shown in Table 8. The acceptance criteria for the SST and CCT

tests shown in Table 8 are as follows. SST (corrosion

resistance of processed part): 4.0 or more, SST (cut part):

1.0 or less, SST (top and bottom of end surface): 0.5 or less,

CCT (cut part): 0 or less, CCT (top and bottom of end

surface): 0.5 or less

[00921

[Table 8] cu E oDu o oooo oooo

E E

oot U) 0000000000000000006660o oo o

1 U t .DD _0U a

-DoEH

- a -aC n 000

oU)U 00 .0n 0 -. 00 0 - 0 - 00 - - -0 .n -I- 0 0 UD F

2 o V) 0 - Oo)U)U) I - U)U)N O L O N

C C L

( (U0-r cn o _0

C -v.2 NS~

(U 0

1.n~~ ~ ~L e -|Nme1n Ln n 't o - Qooo

Hn D rrnNmo-Nmu TU xCO01- NC a O LO M M M M M M M M M M M M M M M M- M- N M

dfl aexH a|dLUeX aldLe.eeXuo

0093]

[Examples 93 to 112, Comparative Examples 22 to 25]

A surface treatment agent was prepared in the same manner

as in Examples 22 to 38 and Comparative Examples 6 to 9 except that metal oxide particles (D), polyurethane resin (E), and block isocyanate resin (F) of types and amounts shown in Table

9 were further added. The test sheet was prepared as follows.

The GI sheet or the GL sheet (both manufactured by Nippon Test

Panel Co., Ltd., sheet thickness 0.35 mm) shown in Table 9

were spray-degreased by Surf Cleaner 155 (manufactured by

Nippon Paint Surf Chemicals Co., Ltd.) at 60°C for 10 seconds,

then spray-washed with water, immersed in a cobalt ion

containing alkaline surface conditioner (NP conditioner 200,

pH 11, 60°C) for 5 seconds, washed with water, and dried at a

PMT of 80°C, and then the treatment agent including the

described components was applied to the GI sheet or the GL

sheet by bar coater #3, followed by drying at a PMT (peak

metal temperature) of 80°C. After the surface treatment, a

urethane-based adhesive was applied, and then an acrylic

laminate film (polypropylene film with a thickness of 50 pm)

was compression-bonded with a roller, heated at 230°C, and

adhesively bonded to obtain the test sheets of Examples 93 to

112 and Comparative Example 22 to 25.

[0094]

[Table 9]

4~ 1 U' j - - - -- -- -- - --- - - -

E

41

SU01 .U)

C:

41 . Cj O' C C C C C r r4 r4 r4

L.

41

41 0 1 00 0 0 ' 0E0oo0 4X (0 NN N N NNN -N N N N

NNFNF-U U < NNNN N NN E U) 401 0141

U') 0

.- 0..1

< .2~ -0 U M-' 0 r-. D0M '-~ ~M M ',-'I 00 0 -I C1 0 0- U

CO 0 o U NIIN I IN onEt Mk lM Il-I

0095C

[Poesn prmr adeso tes (5 ri 0 0InN n testN)] I I I

Th~etetsetwsctwt acutri agrdpten extruded to 8 mm with an Erichsen tester, and then the tape was peeled off. The tape peeling test was carried out according to JIS Z0237: 2009. The degree of tape peeling was evaluated according to the following criteria, and 4 or more was regarded as acceptable. The results are shown in Table 10.

: No peeling, 4.5: 1 to 10% peeling, 4: 11 to 20% peeling,

3.5: 21 to 30% peeling, 3: 31 to 40% peeling, 2.5: 41 to 50%

peeling, 2: 51 to 60% peeling, 1.5: 61 to 70% peeling, 1: 71

to 80% peeling, 0.5: 81 to 90% peeling, 0: 91 to 100% peeling

[00961

[Processing secondary adhesion test (Erichsen test)]

As a pre-processing, the test sheet was cut with a cutter

in a grid pattern, extruded to 6 mm with an Erichsen tester,

immersed in boiling water at 980C for 1 hour, and then tape

peeled from the extruded portion. The degree of tape peeling

was evaluated in the same manner as in the first processing

adhesion test. The results are shown in Table 10.

[0097]

In addition to the above, SST and CCT were set to 1000

hours and evaluation was carried out. The results are shown in

Table 10. Note here that the acceptance criteria for the SST

and CCT tests shown in Table 10 are as follows. SST (cut

part): 5.0 or less, SST (top and bottom of end surface): 6.0

or less, CCT (cut part): 2 or less, CCT (top and bottom of end

surface): 3.5 or less

[00981

[Table 10]

Evaluation

Processing Processing SST1000hr(mm) CCT1000hr(mm) End End End End Stability primary secondary adheion adheion Cut part surface surface Cut part surface surface adhesin a/top /bottom /top /bottom 93 1 5 5 2.9 4.8 2.9 0.9 1.9 1.8 94 1 5 5 3.1 5.1 4.7 1.2 2.1 1.9 95 1 5 5 3.2 5.1 4.2 1.1 1.9 2.2 96 1 5 5 2.9 4.3 3.2 0.8 1.8 1.5 97 1 5 5 3.1 4.5 4.5 0.9 2.2 2.2 98 1 5 5 3.1 4.6 4.3 0.9 2.3 2.3 99 1 5 5 3.2 5.8 5.3 1.3 2.7 2.6 100 1 5 4 2.9 4.4 3.9 0.9 1.8 2.1 101 1 5 5 3.1 4.2 4.1 0.9 2.6 2.2 a 102 1 5 4.5 3.5 4.1 3.9 0.9 2.2 1.9 E S103 1 5 5 3.2 4.2 4.1 0.9 2.2 2.1 Lu 104 1 5 4 3.9 4.4 4.2 1.1 2.2 2.2 105 1 5 5 3.9 4.9 4.5 1.2 2.6 2.5 106 1 5 3 4.5 5.7 5.6 1.8 3.2 3.3 107 1 5 4.5 4.7 5.8 5.5 1.7 3.3 3.4 108 1 5 4.5 4.7 5.8 5.7 1.8 3.4 3.4 109 1 4 4 4.7 5.8 5.7 1.8 3.4 3.3 110 2 4.5 4.5 4.8 5.9 5.7 1.8 3.4 3.2 111 1 5 5 1.8 2.3 2.1 0.6 1.1 1.1 112 1 5 5 1.9 2.5 2.2 0.6 1.1 1.2 22 1 3 2 0.6 6.8 7.1 2.5 4.2 4.1

[ - 23 1 2 2 5.9 6.9 7.2 2.4 4.1 4.2 E a p 24 1 2 2 6.2 6.9 6.9 2.6 4.6 4.8 E x. U 25 - 5 5 2.9 4.8 4.1 1.1 1.8 7

[0099]

The results of the Examples and Comparative Examples show

that the aqueous chromium-free metal surface treatment agents

according to Examples are more excellent in coating adhesion

to the metal base material as compared with the surface

treatment agent according to Comparative Examples, and that a

film capable of withstanding high-strength workability can be

formed on a metal base material.

Claims (10)

1. An aqueous chromium-free surface treatment agent

comprising a bifunctional silane compound (A), a

monofunctional silane compound (B), and an acetylene glycol

based surfactant (C).

2. The aqueous chromium-free surface treatment agent

according to claim 1, wherein a concentration of the

bifunctional silane compound (A) is in a range of 1 to 100 g/L,

a concentration of the monofunctional silane compound (B)

is in a range of 1 to 100 g/L, and

a concentration ratio (A/B) of the bifunctional silane

compound (A) to the monofunctional silane compound (B) is in a

range of 0.1 to 5.

3. The aqueous chromium-free surface treatment agent

according to claim 1 or claim 2, wherein a concentration of

the acetylene glycol-based surfactant (C) is in a range of

0.05 to 1 g/L.

4. The aqueous chromium-free surface treatment agent

according to any one of claim 1 to claim 3, wherein a contact

angle on a mirror-finished aluminum sheet surface is 25 degree

or less.

5. The aqueous chromium-free surface treatment agent

according to any one of claim 1 to claim 4, further comprising

water-dispersible metal oxide particles (D),

wherein an average particle diameter of the water

dispersible metal oxide particles (D) is 150 nm or less, and

a concentration of the water-dispersible metal oxide

particles (D) is in a range of 1 to 20 g/L.

6. The aqueous chromium-free surface treatment agent

according to any one of claim 1 to claim 5, further comprising

a polyurethane resin (E) that is at least any one of a water

dispersible polyurethane resin and a water-soluble

polyurethane resin, and

a concentration of the polyurethane resin (E) is in a

range of 1 to 20 g/L.

7. The aqueous chromium-free surface treatment agent

according to any one of claim 1 to claim 6, further comprising

a block isocyanate resin (F),

wherein a concentration of the block isocyanate resin (F)

is in a range of 1 to 20 g/L.

8. The aqueous chromium-free surface treatment agent

according to any one of claim 1 to claim 7, wherein pH of the

aqueous chromium-free surface treatment agent is in a range of

to 7.

9. A surface treated metal comprising a surface on which a

surface treatment film is formed with an aqueous chromium-free

surface treatment agent according to any one of claim 1 to

claim 8.

10. A surface treatment method comprising a surface treatment

film formation step including treating a surface of an object

to be coated with an aqueous chromium-free surface treatment

agent according to any one of claim 1 to claim 8 to form a

surface treatment film.